Knee Injuries Of The Athlete

Knee  

Anatomy and Biomechanics  

Medial Collateral Ligament Injury  

Anterior Cruciate Ligament Injury  

Posterior Cruciate Ligament Injury  

Knee Dislocation  

Meniscal Tears  

Discoid Meniscus  

Meniscal Cyst  

Patellofemoral Joint  

Anterior Knee Pain Syndrome  

Chondromalacia Patellae  

Acute Dislocation of the Patella  

Recurrent Dislocation of the Patella  

Recurrent Subluxation of the Patella  

Patellar Tendinitis  

Patellar Fracture

 

Patellar Ligament Rupture  

Quadriceps Rupture  

Pre-patellar Bursitis  

Bipartite Patella  

Plica Syndrome  

Ilio-tibial Band Friction Syndrome  

Semimembranous Tendinitis  

Loose Bodies Remember:\ Acute compartment syndrome= Extreme & worsening pain in leg; Chronic compartment syndrome- Gradual onset muscle pain during  

Introduction The knee is the most commonly injured joint in sport. Its size, lack of stability and forward prominence makes it prone to contact and injury (Fig. 1).  

Biomechanics It is a complex hinge joint which allows free flexion and some rotation in flexion. With progressive flexion there is roll-back of the femur on the tibial surface, controlled by tension in the posterior cruciate ligament. The articular surfaces of the tibio-femoral joint have relatively poor congruity and little inherent stability, as is evident on examination of dried bones. The articular congruity is improved by the menisci, but stability is dependent on ligaments, capsule and muscle control.

The knee is vulnerable to high torsional and deceleration forces often encountered in running sports, as well as to contact forces. The key to diagnosis of injury rests with history and clinical examination. A description of the mechanism of injury often gives a clear indication to the likely diagnosis (Fig. 2). A sportsman who describes that he felt his knee dislocate of slip, with pain and a pop when he stepped off it, is providing a fairly classical history of an isolated rupture of the anterior cruciate ligament.  

Ligamentous Injury The medial and lateral collateral ligaments, and the anterior and posterior cruciate ligaments constitute the four major ligamentous structures about the knee. Integrity of these ligaments is important for normal stability and kinematics of the knee, Altered kinematics may lead to degeneration of the knee.  

Medial Collateral Ligament The medial collateral ligament extends from the medial femoral epicondyle, widens and inserts on to the tibia 8 to 10 cm below the jointline. It is orientated in a posterior to anterior direction and is taut in extension. It is susceptible to contact and non-contact injuries involving a valgus force and external rotation force to the knee.  

Examination reveals swelling over the medial aspect of the knee and later bruising may be seen. The knee is typically held flexed and there is a painful soft end point limited extension (pseudo-locking). There is tenderness along the course of the medial ligament, most commonly at the site of femoral insertion. Laxity is assessed with the knee in 30 degrees of flexion and is graded I to III (Figs. 3 and 4). Grade III injury has greater than a centimeter of opening of the medial jointline. If there is instability in extension a more complex ligamentous disruption should be suspected. X-rays are usually normal, although an avulsion fragment is rarely seen. Later, calcification may be seen at the site of femoral insertion (Pellegrini-Stieda lesion).  All isolated medial collateral ligament injuries can be treated conservatively. Early treatment involves RICE with graded quadriceps strengthening. In normal gait there is a closing force on the medial jointline and so early weight bearing can be allowed and bracing is not always required for Grade I to II injury. Bracing is indicated in Grade III injuries and where the patient feels instability on weight bearing. Recovery from a Grade I to II injury is usually between 3 and 4 weeks and for a more significant injury 6 to 8 weeks.

 

Lateral Collateral Ligament Injury  

The lateral collateral ligament extends from the lateral femoral epicondyle to the head of the fibula. Isolated ruptures are rare and the ligament is more commonly injured in association with disruption of the posterolateral corner. Usually require surgical reconstruction.  

NOTE; ES HAS CHARACTERIZED THE QUADS AS ACTING ON A PLATFROM STABLIZED BY THE ACL, CONVERSELY, THE HAMSTRINGS ACT ON THE PATFORM STABLIZED BY THE PCL.  

Anterior Cruciate Ligament Rupture of the anterior cruciate ligament is the commonest major ligamentous knee injury in athletes. The anterior cruciate runs from the postero-superior aspect of the lateral wall of the intercondylar notch in the femur to the tibial spines. The ligament averages 12 mm in thickness and has 2 major bundles, the anteromedial(tight in flexion) s and the posterolateral (tyight in extension).. The anterior cruciate ligament is a primary stabiliser to anterior tibial translation and also controls the rotational screw-home mechanism in terminal knee extension. Eighty percent of anterior cruciate ligament ruptures are as a result of non-contact injury. The ligament is ruptured by an internal rotational and anterior translation force to the tibia caused by pivoting or cutting or landing awkwardly from a jump. It is also ruptured by hyperextension of the knee and will fail with progressive valgus in combination with a medial collateral ligament tear. In isolated non-contact injuries the patient will describe stepping off the knee at speed and feeling pain associated with a pop and giving way. Swelling is almost immediate, consistent with a haemarthrosis and a POP sensation.(Figs 5 and 6). In the absence of fracture 80% of acute knee haemarthrosis are due to rupture of the anterior cruciate ligament. Examination reveals an effusion and the knee is often held flexed. There may be tenderness over the anterolateral jointline where there is commonly an associated capsular injury. The dynamic Lachman test is positive (Fig. 7) and depending on the amount of pain and spasm static Lachman and pivot shift test may also be elicited. Plain x-ray may reveal an avulsion fracture involving the tibial spine, particularly in younger patient groups.

There may also be avulsion fracture from the anterolateral tibia, so called

Second fracture. An MRI scan will usually demonstrate the ruptured ligament.

Treatment of anterior cruciate ligament ruptures is determined by associated injuries (meniscal, ligamentous), degree of instability and patient expectation (Fig. 7). All patients can be managed initially conservatively with treatment directed at settling the effusion, regaining range of motion and a muscle strengthening programme. Patients who have persistent jointline symptoms or locking may have meniscal pathology which requires arthroscopy. Patients who have an associated Grade III rupture of the medial collateral ligament are probably better served by early cruciate reconstruction. Otherwise, anterior cruciate reconstruction is reserved for patients intending to return to high demand sports or those with symptomatic ongoing instability.  

Chronic Anterior Cruciate Insufficiency Following isolated rupture of the anterior cruciate ligament most knees settle down over 6 to 12 weeks. Although the ligament does not heal up to one third of patients may be asymptomatic. Another group may only have symptoms with high demand sports such as football, netball or skiing. A smaller group of patients have marked instability such that they are at risk even crossing the road. Symptoms of anterior cruciate insufficiency included giving way associated with pain and recurrent swelling with repeated episodes of giving way there may be injury to the menisci and osteochondral trauma with an increased likelihood of the development of degenerative arthritis. Examination reveals usually good muscle tone and often no effusion. The range of motion is preserved. The Lachman, pivot shift, and anterior draw tests are positive. McMurray’s test will indicate whether there is associated meniscal pathology. For a patient who suffers occasional instability with high demand sports, modification of activity and an intensive lateral hamstring strengthening programme may be all that is required. Other patients with symptomatic instability can be offered anterior cruciate reconstruction (Fig. 8). The results following surgery suggest that up to 85% of patients will be able to return to their pre-injury level of sport. Laxity of the graft has been shown to gradually increase over the years following reconstruction, but the patients often remain asymptomatic. There is not strong evidence at this stage that reconstruction influences the development of osteoarthritis.  

Posterior Cruciate Ligament Rupture The posterior cruciate ligament courses from the anterior portion of the medial wall of the intercondylar notch of the femur to insert into the central posterior tibia, approximately 1 cm below the jointline. The ligament is composed of anterolateral and posteromedial bands. The posterior cruciate ligament is the primary restraint to posterior tibial translation. The posterior cruciate ligament can be ruptured by a direct blow on to the anterior upper tibia, such as a heavy fall on a flexed knee or a dashboard injury. It will also fail in hyperextension and in more complex posterolateral or posteromedial disruption.

The acute symptoms may be mild and isolated ruptures may be missed (Fig. 9). Examination should elicit a posterior sag with tibial drop back (Fig. 10). Plain x-rays may show an avulsion fracture involving thee tibial insertion (this type of rupture should be treated operatively). An MRI scan will demonstrate the ligament tear. Treatment of mid-substance ruptures has been non-operative involving intensive quadriceps strengthening. However, a posterior cruciate deficient knee may develop osteoarthritis (due to the altered kinematics). Patients develop patellofemoral pain with degeneration of the patellofemoral and medial compartments. Early reconstruction is probably better for young patients.  

Knee Dislocation (EMERGENCY-INVESTIGATE THORUGHLY WITH VASCULAR STUDIES TO AVOID AMPUTATION) Complete knee dislocation is an orthopaedic emergency with injury to the popliteal artery and common peroneal nerve (when lateral).

Both the anterior and posterior cruciate

ligaments are torn as well as the collaterals (Figs. 11 and 12). Vascular injury after knee dislocation=30 to 50% Immediate reduction is necessary and then splinting. Close monitoring of circulation is essential and angiography performed if there is any doubt concerning circulation. (Delayed occlusion of the popliteal artery may occur due to an internal flap tear). Surgical reconstruction of the knee is usually required.  

Meniscal Tears Joint line pain with locking. The menisci are fibrocartilaginous semilunar structures on the tibial surface. Their function is to improve the congruity of the tibiofemoral articulation and to transmit load. They also function as shock absorbers and improve knee joint stability. Following meniscectomy the contact area in the compartment is reduced and contact pressures may be increased by more than 350%. Shock absorbing capacity is reduced and as a result of these factors meniscectomy has been shown to lead to development of osteoarthritis. The menisci are relatively avascular with blood supply limited to the peripheral one quarter to one third (see Fig. 33, Chapter 18). (Tears in the vascular region have the potential for healing). Medial meniscal tears are 3 times more common than lateral meniscal tears.  

A meniscus is torn by being trapped between the two bone surfaces when a rotary force is applied to a loaded knee (twisting when rising from a full squat) (Fig. 13).  

There is joint line pain, delayed effusion and with a bucket handle tear the knee will be locked. With less dramatic tears there is usually a history of recurrent clicking and catching and jointline pain.  

‘The signs include effusion, wasting of the quadriceps, pain on forced extension, pain on forced flexion and a positive McMurray’s test.  

An MRI scan will exclude other pathology.  

Arthroscopy allows good visualization and partial meniscectomy (Fig. 14). Peripheral bucket handle and incomplete bucket handle tears (in young patients) should be repaired (Fig. 15). Where there is an associated anterior cruciate ligament rupture this may need to be reconstructed to decrease the risk of recurrence of the meniscal tear. (Unhappy “Triad” is medial collateral/anterior cruciate ligament/medial meniscal injury combination).  

Discoid Meniscus (Fig. 16). A meniscus, usually the later, which is not the usual C-shaped but nearly covers the whole plateau (2 types: complete/incomplete). There may be mechanical symptoms of jointline pain and “clunking”. Partial meniscectomy may be required.  

Meniscal Cyst (Fig. 17). Usually arise from a horizontal cleavage tear of the lateral meniscus.  

Patellofemoral Joint Problems The patella is a sesamoid bone in the quadriceps tendon (present at seven and a half weeks gestation). It functions to improve the efficiency of the quadriceps mechanism by lengthening the movement arm decreasing friction, improving stability and centralizing the quadriceps muscle pull and to protect the anterior aspect of the joint. The stability of the patella is provided by the bony anatomy of the trochlear groove and patella, static tension in the soft tissues of the medial and lateral retinaculum and the dynamic control of the quadriceps mechanism. The vastus medialis oblique muscle is particularly important in maintaining patellofemoral balance and normal tracking. Acute injuries to the patellofemoral joint include direct trauma, subluxation or patella dislocation, patellar fracture, quadriceps tendon or patellar ligament rupture. Many patients however, present with anterior knee pain without a history of specific traumatic incident.  

Chronic)Patello-femoral pathology(arthritis)= Pain after sitting & with stars climbing; On exam:patella creptitus and patella grind,  

Anterior Knee Pain Syndrome Anterior knee pain is the commonest sports knee complaint. Its pain may be well localised (patellar tendinitis), but more usually vaguely anterior. The pain is usually aggravated by loading a flexed knee (as in climbing stairs or inclines). There is sharp retropatellar pain after sitting for prolonged periods, crepitus, catching, weakness and giving way and an effusion. The causes of anterior knee pain syndrome are myriad, and often physical examination is unremarkable other than for retropatellar crepitus (Fig. 18).  

Figure 18 Anterior Knee Pain Syndrome Patello­femoral problem= Pain after sitting & with stars  climbing with  patella creptitus and patella grind,   ∙                 Trauma (Osteochondral injury)   ∙                 Mal­alignment Anatomical pre­disposition Muscle imbalance Patellar subluxation Patella dysplasia   ∙                 Compressive Excessive lateral pressure syndrome Hamstrung patella   ∙                 Over­use Patellar tendinitis Medial plica syndrome Rentinacular irritation Osgood­Schlatter’s disease Bipartite patella  

∙                 Degenerative/Inflammatory   ∙                 Idiopathic             Primary chondromalacia    

Eighty percent of patients with anterior knee pain syndrome respond to non-operative measures. Precipitating and aggravating activities should be identified and avoided. A physiotherapy programme should include quadriceps strengthening and in particular vastus medialis toning, together with hamstring stretching. Patellar taping may be of benefit. A response is usually seen within 6 to 8 weeks, but if not the diagnosis should be reassessed and onward referral or further investigation undertaken.  

Chondromalacia Patellae (Fig. 19)  

This is softening of the patella cartilage either from a direct blow or mal-alignment (with patellar subluxation). Typically seen in young overweight girls with knock-knees. The cartilage damage can be classified (Fig. 20).  

Acute Dislocation of the Patella A pop with knee swelling. The mechanism of injury usually involves an external rotation and valgus force with the knee in near extension or a direct blow to the patella. The patient may present with the patellar dislocated in which case the diagnosis is obvious and reduction is usually readily achieved by gentle extension of the knee. However, spontaneous reduction often occurs soon after injury. The clinical signs include haemarthrosis, tender medial patellar retinaculum, a positive patella apprehension test and patellar instability. An x-ray is essential to exclude a significant osteochondral fracture. If this is present arthroscopy and excision of the fragment is indicated.  

A tense haemarthrosis may be drained for pain relief. The knee should be immobilized in extension and a removal splint is usually adequate. The patient is instructed in isometric quadriceps exercises and may weight bear as comfort allows. As the effusion resolves graduated flexion may be commenced and the knee immobilizer can usually be discarded by three weeks. The patient should not return to sport until they have regained normal quadriceps muscle tone and bulk and a negative apprehension test.  

Recurrent Dislocation Recurrent dislocation is usually clear on history and if there is not a response to an extensive quadriceps strengthening programme surgery is indicated (a lateral release and repair or advancement of the medial retinacular tissue and vastus medialis, if intraoperatively this does not achieve stability a distal bony re-alignment may be indicated).  

Recurrent Subluxation Symptoms include anterior knee pain and giving way. Examination may reveal anatomical features predisposing to patellar subluxation, including increased Q angle (line of pull of the quadriceps) due to valgus or rotational factors, out-turned patellae or patellar alta. The patella may track in a J-curve (Fig. 21). The patella may be subluxable or dislocatable, and lateral retinacular tightness may be evident. X-rays (with skyline views) and CT scan may show patella dysplasia or subluxation. If there is no improvement with a protracted conservative programme, surgery is necessary (with soft tissue or bony re-alignment).  

Patellar Tendinitis (Jumper’s Knee) This is an over-use injury, commonly seen in basketball. There is anterior knee pain (with exertion). Examination reveals point tenderness over the central insertion of the patellar ligament into the patella and there may be some swelling over the overlying soft tissues with palpable crepitus. The hamstrings and gastrocnemiae should be assessed for tightness. An MRI scan will confirm altered signal at the site of the degenerative tendon. A bone scan may show increased uptake at the site of tendon insertion. Treatment includes rest with modification of aggravation activities (such as jumping). A graduated exercise programme should be provided to strengthen the quadriceps, combined with intensive stretches for the hamstrings and gastrocnemiae. The overlying bursa may be injected with corticosteroid and local anaesthetic in protracted cases. If symptoms extend beyond one year despite conservative management, surgical debridement of the degenerative tendon with a segment of the patellar bone may be considered.  

Patellar Fracture Injury with dorsiflexed foot. Caused by direct impact on the patella as in a fall on a flexed knee or a dashboard injury. May also occur following violent resisted contraction of the extensor mechanism. If there is disruption of the extensor mechanism (indicated by a lag on examination or a significant gap on x-ray) surgical repair is essential (Fig. 22). Undisplaced or minimally displaced fractures with preservation of the extensor mechanism may be treated non-operatively, by splinting in extension for 6 weeks.  

Quadriceps Tendon Rupture (Bill Clinton’s injury) Caused by sudden resistance to a strong quadriceps contraction. Seen in the older patient group (as with other tendon degeneration conditions). There is pain with loss of quadriceps function, a lag and a palpable gap. When the diagnosis is unclear and particularly when presentation is delayed MRI can define the integrity of the tendons. To restore good quadriceps function operative repair is required.  

Patellar Ligament Rupture Occurs in younger patients by the same mechanism as quadriceps tendon rupture. Caused by penetrating injuries (dashboard). There is pain and loss of quadriceps function with a significant lag. The defect is usually palpable. Surgical repair is indicated.  

Pre-patellar Bursitis Severe pain with subtle signs of crpitus. Surtgery often helps. The bursa over the anterior aspect of the patella is prone to injury and inflammation from repetitive contact (seen in football players and gymnasts). Once a significant episode has occurred there is a tendency to become recurrent. Examination reveals enlargement of the thickened bursa with crepitus. Acute cases have signs of inflammation and there may be secondary infection with cellulitis.  

Inflammatory bursitis is treated with RICE and NSAIDS. Padding and protecting the area on return to sport is important to minimize the risk of recurrence. Where there is secondary sepsis antibiotics are needed and surgical draining of an abscess. Recurrent or chronic bursitis will eventually require excision of the thickened bursa.  

Bipartite Patella (accessory ossification centre) Present in <15% of patellae and usually asymptomatic and usually at the superolateral corner. Symptoms may occur after direct contact injury or overuse. Symptoms include anterior knee pain and tenderness. There is tenderness over the site of the pseudoarthrosis. X-rays show the bipartite patella (a bone scan may be helpful in cases following significant trauma). Most cases settle with a conservative programme as in the Management of Anterior Knee Pain Syndrome. Rarely is excision of the fragment required.  

Plica Syndrome Synovial plicas are common and often seen at arthroscopy (Figs. 23 and 24). They may become a source of symptoms following a direct injury causing thickening and scarring of

the plica, or from over use. There is an anterior knee pain syndrome with occasional clicking and snapping and tenderness over the medial femoral condyle.  

Those that do not settle with rest and a conservative programme may be treated by arthroscopic resection.  

Ilio-tibial Band Friction Syndrome Seen in joggers and distance runners. There is inflammation over the lateral epicondyle caused by rubbing of the ilio-tibial band (Fig. 25). Examination reveals point tenderness over the lateral epicondyle, pain is reproduced as the ilio-tibial band passes back and forth over the lateral epicondyle. There may be tightness of the tensor fascia lata and hamstring muscles.  

Treatment involves rest and a set of exercises to stress the ilio-tibial band and hamstring muscles. A break of three months from distance running is usually required.  

Semimembranous tendinitis This is seen in male athletes and may be difficult to diagnose (postero-medial knee joint pain with hamstring spasm). A cyst may occur which is difficult to excise (Fig. 26).  

Loose Bodies Loose bodies cause mechanical symptoms of locking and recurrent effusions. Occasionally they can be palpated. They can be due to a meniscal fragment or osteochondral fragment (traumatic, degenerative, osteochondritis dissecans) or synovial chondromatosis (Fig. 27). X-rays will demonstrate radio-opaque loose bodies. Treatment by arthroscopic removal is usually successful.